1. Field of the Invention
The present invention relates to an ink-jet head and a head unit that eject an ink to a recording medium.
2. Description of the Related Art
For example, U.S. 2005/0122354A1 discloses an ink-jet head in which so-called end dot deflection is reduced. This ink-jet head has plural recording element substrates. Recording areas of the recording element substrates are arranged to overlap one another.
When ink droplets are ejected at high recording density, ink droplets ejected from nozzles located at both the ends of an ink-jet head deviate toward the center of the ink-jet head. This phenomenon is referred to as “end dot deflection”. In this ink-jet head, correction for adjusting the number of recording elements used for actual ejection is performed according to recording density. A stable image with a fixed quality is obtained according to this correction.
Further, U.S. 2005/0212854A1 discloses an ink-jet head that provides a time difference when ink droplets are landed on a recording medium. In this ink-jet head, plural head chips are arranged in a zigzag shape to function as one long ink-jet head as a whole. In forming dots on the recording medium in this ink-jet head, when dots adjacent to one another have to be formed, the dots are formed with a time difference equal to or longer than time in which an ink is absorbed by the recording medium. This prevents ink droplets from combining on the recording medium to damage a desirable dot shape.
However, in the invention disclosed in US 2005/0122354A1, it is necessary to perform correction for adjusting recording elements actually used for ejection. Thus, it is likely that adjustment of the ink-jet head takes time. Further, since there are nozzles not used for ejection, the nozzles are wasted.
In the invention disclosed in US 2005/0212854A1, there is no indication about end dot deflection. Thus, it is likely that, when end dot deflection occurs, it is impossible to cope with the end dot deflection.
It is an object of the invention to provide an ink-jet head that can cope with “end dot deflection” of an ink with a simple structure.